Liquid crystal display and backlight module thereof

ABSTRACT

A backlight module including a first frame, a light guide plate, and a light source is provided. The inner surface of the first frame has at least a first reflection area. In addition, the light guide plate is disposed in the first frame and located beside the first reflection area, and the light guide plate has a light incident surface. Moreover, the light source is disposed in the first frame and between the first reflection area and the light incident surface. A liquid crystal display using the backlight module is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of a prior applicationSer. No. 11/565,629, filed on Dec. 1, 2006. The prior application Ser.No. 11/565,629 claims the priority benefit of Taiwan application serialno. 95136697, filed on Oct. 3, 2006. All disclosure of the Taiwanapplication Ser. No. 95136697 and the prior application Ser. No.11/565,629 is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display. Moreparticularly, the present invention relates to a backlight module for aliquid crystal display.

2. Description of Related Art

A common liquid crystal display usually includes a component with colordisplay function, such as a liquid crystal display panel. As the liquidcrystal display panel does not emit light, a backlight module must bedisposed below the liquid crystal display panel to serve as a lightsource to illuminate the liquid crystal display panel for displayingimages.

FIG. 1 is a schematic sectional view of a conventional backlight module.Referring to FIG. 1, the conventional backlight module 100 includes afirst frame 110, a second frame 120, a light source 130, a lampshade132, a light guide plate 140, a reflector 150, and a diffuser film 160.The light source 130 and the lampshade 132 are disposed in the firstframe 110, and the light guide plate 140 is disposed beside the lightsource 130. In particular, a part of the light L emitted from the lightsource 130 enters the light guide plate 140 after being reflected by thelampshade 132.

In addition, the reflector 150 is disposed at the bottom of the lightguide plate 140, and the diffuser sheet 160 is disposed at the top ofthe light guide plate 140. In detail, the light that enters the lightguide plate 140 is reflected by the reflector 150, and emits out throughthe diffuser film 160, so as to provide a uniform light source to theliquid crystal display panel (not shown). It should be noted that thelampshade 132 is generally made of a metal material, which not only moreexpensive, but also is heavy. Especially when a large-size backlightmodule 100 is assembled or is reworked, the lampshade 132 consumes themuch time of the process, which adversely impacts the productionthroughput.

SUMMARY OF THE INVENTION

The present invention is directed to a backlight module, for solving theproblem of high manufacturing cost.

The present invention is directed to a liquid crystal display includingthe aforementioned backlight module so as to improve the display qualityand reduce the manufacturing cost of the liquid crystal display.

To achieve the aforementioned or other purposes, the present inventionprovides a backlight module including a first frame, a light guideplate, a light source, an optical film, and an optical film set. Thefirst frame includes at least a first reflection area on an innersurface thereof. The light guide plate is disposed in the first frameand located beside to the first reflection area. The light guide platehas a light incident surface. The light source is disposed in the firstframe and between the first reflection area and the light incidentsurface. The optical film is disposed on the first reflection area ofthe first frame, beside the light incident surface, and between thelight source and the first frame. The light incident surface faces theoptical film, and the optical film is a brightness enhancement film or aprism sheet. The optical film set is disposed above the light guideplate. The light guide plate is disposed between the first frame and theoptical film set. The optical film is separate from the optical filmset.

According to an embodiment of the present invention, the backlightmodule further includes a second frame disposed on the first frame. Thesecond frame includes an opening to expose the light guide plate, and aninner surface of the second frame includes at least one secondreflection area.

According to an embodiment of the present invention, the optical film isfurther disposed on the first reflection area of the first frame and thesecond reflection area of the second frame.

According to an embodiment of the present invention, the optical filmset at least includes a diffuser film, a prism sheet or a brightnessenhancement film, or a combination thereof.

According to an embodiment of the present invention, the backlightmodule further includes a reflector disposed between the optical filmand the first reflection area of the first frame.

The present invention provides a liquid crystal display which comprisesthe aforementioned backlight module and a liquid crystal display panel,wherein the liquid crystal display panel is disposed above the lightguide plate.

The first reflection area of the first frame effectively reflects a partof the light emitted from the light source to the light guide plate.Therefore, the backlight module of the present invention can effectivelyreflect the light without using a lampshade. Thus, the manufacturingcost is reduced, and the assembly time is also reduced. The first frameand the second frame of the backlight module of the present inventioncan also be assembled together to further improve the reliability of thebacklight module. The second frame of the present invention has thesecond reflection area which effectively reflects a part of the lightemitted from the light source to the light guide plate, thus furtherimproving the reuse rate of the light, such that the liquid crystaldisplay has good display quality.

In order to make the aforementioned and other purposes, features andadvantages of the present invention comprehensible, preferredembodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a conventional backlight module.

FIG. 2 is a schematic sectional view of a backlight module according toa first embodiment of the present invention.

FIG. 3 is a schematic sectional view of a backlight module according toa second embodiment of the present invention.

FIG. 4 is a schematic view of an optical film of the second embodimentaccording to an embodiment of the present invention.

FIG. 5 is a schematic sectional view of the backlight module accordingto a third embodiment of the present invention.

FIG. 6 is a schematic view of the liquid crystal display according to afourth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS The First Embodiment

FIG. 2 is a schematic sectional view of the backlight module of thefirst embodiment of the present invention. Referring to FIG. 2, thebacklight module 200 of the present invention includes a first frame210, a light guide plate 220, and a light source 230. The inner surfaceof the first frame 210 has at least a first reflection area 210 a, andthe position of the first reflection area 210 a corresponds to theposition of the light source 230. It should be noted that the firstframe 210 of the present invention can be comprised of a hightemperature resistant material of high reflectivity, for example, ametal material with high-reflectivity painting or coating, a plasticmaterial added with high-reflectivity particles, a sheet material ofhigh reflectivity, or the like. In other words, because the first frame210 of the present invention can withstand the high temperature so thatit will not get deformed even when the temperature of the backlightmodule 200 is very high after a long time use.

In addition, the light guide plate 220 is disposed in the first frame210 and is located beside to the first reflection area 210 a. Generallyspeaking, the light guide plate 220 includes a light incident surface220 a, a light emitted surface 220 b, and a light diffusion surface 220c. In detail, a part of the light L emitted from the light source 230enters the light guide plate 220 through the light incident surface 220a after being reflected by the first reflection area 210 a. Thereafter,the light is diffused by the light diffusion surface 220 c. Finally thelight emits out through the light emitted surface 220 b.

According to another aspect of the present invention, in order to firmlyposition the light guide plate 220 in the first frame 210, the firstframe 210 of the present invention includes at least a first positioningportion 212. The first positioning portion 212 is located at the edge ofthe first reflection area 210 a, so as to position the light guide plate220. It should be noted that the first positioning portion 212 of FIG. 2comprises a stair-case structure, however the shape of the firstpositioning portion 212 may be properly modified according to differentrequirements, and is not limited herein.

Moreover, the light source 230 is disposed in the first frame 210 andbetween the first reflection area 210 a and the light incident surface220 a. The light source 230 may be a cold cathode fluorescent lamp(CCFL) or a light-emitting diode (LED). If the CCFL is used as the lightsource 230, as the light L emitted from the CCFL has a slight directionconcentration, a part of the light L emitted towards the inner surfaceof the first frame 210 may enter the light guide plate 220 through thelight incident surface 220 a after being reflected by the firstreflection area 210 a, and thus the application rate of the light L isimproved effectively. The backlight module 200 of the present inventionreflects light by using the first frame 210 made of a high-reflectivitymaterial, and does not need the conventional lampshade 132 (as shown inFIG. 1). Compared with the conventional backlight module 100 (as shownin FIG. 1), the backlight module 200 of the present invention includesfewer components, so the weight and the manufacturing cost of thebacklight module 200 are reduced effectively. Furthermore, the time forassembling or reworking the backlight module 200 of the presentinvention can be effectively reduced as well.

To further improve the optical display quality of the backlight module200, the backlight module 200 of the present invention further includesan optical film set 270 disposed above the light guide plate 220.Moreover, the backlight module 200 of the present invention furtherincludes a reflector 280 disposed at the bottom of the light guide plate220. The optical film set 270 of the present invention includes at leasta diffuser film, a brightness enhancement film (BEF), and a prism sheet,or a combination thereof. The diffuser film can diffuse the lightemitted from the light source 220 more uniformly, the BEF enhances thebrightness of the backlight module 200, and the prism sheet improves thecorrectness of the light exit direction.

The Second Embodiment

The second embodiment is similar to the first embodiment, while thedifference mainly lies in that the backlight module 300 (as shown inFIG. 3) of the present invention farther includes a second frame 240. Tofurther improve the reliability of the backlight module 300, the secondframe 240 of the present invention is disposed on the first frame 210,and the second frame 240 has an opening A to expose the light guideplate 220. It should be noted that the material of the second frame 240and the first frame 210 of the present invention can be comprised of ahigh temperature resistant material of high reflectivity, for example, ametal material with high-reflectivity painting or coating, a plasticmaterial added with high-reflectivity particles, a sheet material ofhigh reflectivity, or the like. Moreover, the inner surface of thesecond frame 240 has at least a second reflection area 240 a.

It should be noted that the second reflection area 240 a and the firstreflection area 210 a are suitable for reflecting a part of the lightemitted from the light source 230 to the light incident surface 220 a.In practice, the position of the second reflection area 240 acorresponds to that of the light source 230. It is known clearly fromFIG. 3 that the second frame 240 of the present invention has at least asecond positioning portion 242 located at the edge of the secondreflection area 240 a. The second positioning portion 242 is against thelight guide plate 220, so as to position the light guide plate 220.

Moreover, the backlight module 400 (as shown in FIG. 4) of the presentinvention further includes an optical film 250, and the optical film 250is disposed on the first reflection area 210 a of the first frame 210and the second reflection area 240 a of the second frame 240. Theoptical film 250 includes at least a reflector, a BEF, and a prismsheet, or a combination thereof, so as to further improve the reuse rateof the light source 230.

The Third Embodiment

The third embodiment is closely similar to the second embodiment, whilethe difference mainly lies in that the backlight module 500 (as shown inFIG. 5) of the present invention further includes a positioning metalpiece 260, and the second frame 240 has a retaining recess 240 b. Thepositioning metal piece 260 of the present invention is disposed betweenthe first reflection area 210 a of the first frame 210 and the opticalfilm 250, and the positioning metal piece 260 extends into the retainingrecess 240 b, so as to position the second frame 240 and the first frame210. The positioning metal piece 260 is made of a high-reflectivitymaterial, and the surface of the positioning metal piece 260 is polishedto further improve the reflection effect for the light source 230.

The Fourth Embodiment

FIG. 6 is a schematic view of the liquid crystal display of the fourthembodiment of the present invention. Referring to FIG. 6, the liquidcrystal display 600 of the present invention includes the aforementionedbacklight module 200 and a liquid crystal display panel 610. Thestructure of the backlight module 200 has been clearly disclosed in thefirst embodiment, and the liquid crystal display panel 610 is disposedabove the light guide plate 220. The liquid crystal display panel 610 ofthe present invention together with the backlight module 300, 400, or500 can form a liquid crystal display. Here, the structures of thebacklight modules 300, 400, and 500 have been clearly disclosed in thefirst and the second embodiment. By using the backlight module 200, 300,400, or 500 of the present invention, the liquid crystal display of thepresent invention has the advantages of light weight, less time requiredfor assembling and reworking, low manufacturing cost, and good opticaldisplay characteristic.

To sum up, the first frame of the backlight module of the presentinvention is made of a high-reflectivity material, and the firstreflection area of the first frame effectively reflects a part of thelight emitted from the light source to the light guide plate. Therefore,the backlight module of the present invention can effectively reflect apart of the light emitted from the light source to the light guide platewithout using the lampshade. Thus, the backlight module of the presentinvention provides an area light source with high luminance, such thatthe liquid crystal display of the present invention has favorableoptical display characteristic. Moreover, as the backlight module of thepresent invention uses fewer components, the backlight module of thepresent invention has the advantages of light weight, low manufacturingcost, and short assembly time, and the working hours for reworking areeffectively reduced as well. The second frame of the present inventionis made of a high reflectivity material, and the first frame and thesecond frame can be assembled together. Thus, the reliability of theentire backlight module and the reuse rate of the light are furtherimproved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A backlight module, comprising: a first frame, comprising at least a first reflection area on an inner surface thereof; a light guide plate, disposed in the first frame and located beside to the first reflection area, wherein the light guide plate has a light incident surface; a light source, disposed in the first frame and between the first reflection area and the light incident surface; an optical film, disposed on the first reflection area of the first frame, beside the light incident surface, and between the light source and the first frame, wherein the light incident surface faces the optical film, and the optical film is a brightness enhancement film or a prism sheet; and an optical film set disposed above the light guide plate, wherein the light guide plate is disposed between the first frame and the optical film set, and the optical film is separate from the optical film set.
 2. The backlight module of claim 1, further comprising a second frame disposed on the first frame, wherein the second frame comprises an opening to expose the light guide plate, and an inner surface of the second frame comprises at least one second reflection area.
 3. The backlight module of claim 2, comprising the optical film further disposed on the first reflection area of the first frame and the second reflection area of the second frame.
 4. The backlight module of claim 1, wherein the optical film set at least comprises a diffuser film, a prism sheet or a brightness enhancement film, or a combination thereof.
 5. The backlight module of claim 1, further comprising a reflector disposed between the optical film and the first reflection area of the first frame.
 6. A liquid crystal display comprising: the backlight module of claim 1; and a liquid crystal panel, disposed above the light guide plate. 